Circle cutting attachment for torches



Sept. 16, 1958 R. E. LAMB 2,

CIRCLE CUTTING ATTACHMENT FOR TORCHES Filed Oct. 1, 1956 Russell E. L omb INVENIOR.

Unite States This invention generally relates to an attachment for cutting torches and more particularly involves an attachment for cutting circles with such cutting torches.

An object of the present invention is to provide a circle cutting attachment for cutting torches in which the device is especially adapted for use in cutting circles in materials having irregular surfaces such as pipes or the like.

In certain industries such as the oil industry, considerable field work must be done in connecting pipe lines and especially fittings of the saddle type such as a saddle T is quite often connected to a pipe and this necessitates the cutting of a circular aperture in the pipe. Accordingly, it is the primary object of the present invention to provide a circle cutting attachment for torches which is especially adapted for cutting apertures in pipes but which may be employed with equal facility for cutting circles in any material of this nature.

A further object of the present invention is to provide a circle cutting attachment for torches including a permanent magnet for mounting the attachment on the material being cut wherein the magnet is provided with a shielding plate which permits the attachment to be stored in the tool box of the person employing the device without the magnet attracting other small tools or implements normally appearing in the tool box.

Other objects of the present invention will reside in its simplicity of construction, adaptation for its particular purposes and its relatively inexpensive manufacturing cost.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawing forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is a plan view of the circle cutting attachment of the present invention;

Figure 2 is a side elevational view of the construction of the invention illustrated in conjunction with a cutting torch;

Figure 3 is a detailed sectional view taken substantially upon a plane passing along section line 3-3 of Figure 2 illustrating further structural details of the invention and the manner of attachment to a torch;

Figure 4 is a vertical sectional view taken substantially upon a plane passing along section line 4-4 of Figure 2 illustrating the details of construction of the guide wheel;

Figure 5 is an elevational view of a stationary adjustable wheel which may be substituted for the spring loaded wheel illustrated in Figures 2 and 4;

Figure 6 is a detailed sectional view taken substantially upon a plane passing along section line 6-6 of Figure 2 illustrating the manner of attachment of the permanent magnet; and

Figure 7 is a detailed sectional view similar to Figure 6 but illustrating a pointed marker substituted for the permanent magnet which may be employed for engage- Patented Sept. 16, 1958 ment with an indentation for retaining the circle cutting attachment in the desired position.

Referring now specifically to the drawings, the numeral 10 generally designates the circle cutting attachment of the present invention which includes an elongated bar 12 of polygonal configuration and which may be conveniently square. One end of the bar 12 is provided with an ear or lug 14 for disposition and alignment with an ear 16 on one end of a short bar or mounting bar 18.

The bar 12 is provided with a slidable bracket 20 having a polygonal aperture 22 therein slidably receiving the bar 12 with a screw threaded setscrew 24 extending inwardly from the outer edge of the bracket Zil for locking the bracket 20 longitudinally on the bar 12. The setscrew 24 may be provided with a knurled thumb screw construction as illustrated by the numeral 26 or may be of any other suitable construction in the form of a thumb screw, wing screw or the like. In perpendicular relation to the transverse bore 22 is a vertical cylindrical bore 28 slidably receiving a cylindrical shaft 30 that has an upper end provided with a washer 32 and a lock pin 34 for locking the shaft 36 in the bore 28. The lower end of the shaft 30 terminates in a laterally extending portion 36 and a compression coil spring 33 is disposed between the lower surface of the bracket 30 and the laterally extending portion 36 thereby urging the laterally extending portion 36 to a lowermost position but permitting upward movement thereof against the tension of the spring 38.

A U-shaped attaching bracket 40 is provided on the upper end of a permanent magnet 42 of cylindrical configuration with the bight portion of the U-shaped bracket 40 being pivotally secured thereto by a screw member 44 whereby the bracket 40 may swivel about a substantially vertical axis. The legs of the U-shaped bracket 40 receive the laterally extending portion 36 of the shaft 30 and a hinge pin 46 extends therethrough for hingedly attaching the shaft 36 to the bracket 46) for permitting pivotal movement about the axis of the pivot pin 46. The

lower end of the magnet 42 is provided with a shielding plate 48 of circular construction which may be disposed over the end of the magnet 42 for shielding the same to permit the attachment to be placed in the tool box without the magnet 42 attracting other small tools orimplements normally disposed therein. The magnet 42 is of the cylindrical type with a cylindrical portion of magnetic material disposed in spaced relation to the periphery of the magnet body 42. The plate 48 is of non-ferrous material and provided with a pointer 47 and pin 49 extending into a socket in magnet 42.

As illustrated in Figure 7, a pointed pin 50 may be substituted for the shaft 30 and the pointed pin 50 may be retained in adjusted position by a setscrew 52.

The mounting shaft 18 is provided with a circular bearing member 54 formed integrally therewith with the bearing member 54 including a plurality of ball bearings 56 with the outer race 58 forming an integral part of the shaft 18 and the inner race 66 receiving an adapter 62 having a cylindrical bore 64 with a screwthreaded external portion 66 and a polygonal portion 68 for receiving a suitable wrench for directly attaching the adapter 62 to the cutting torch 70 wherein the cutting torch 70 may rotate in relation to the shaft 18. The lower end of the adapter 62 is provided with a peripheral groove for receiving a split retaining ring 72 which also retains a closure plate 74 for the lower end of the bearing 54 thereby sealing the bearing 54 to prevent entry of foreign material.

The outer end of the mounting shaft 18 is provided with a vertical polygonal bore 76 receiving a polygonal sleeve 78 having a longitudinal cylindrical bore 80 therein. The sleeve 78 is retained in adjusted position by a setscrew 82 and the sleeve 78 slidably and rotatably receives a shaft 84 retained in the sleeve 78 by a transverse pin 86 across the upper end of the sleeve 78 and a compression spring 88 engaging the lower end of the vsleeve 78. The lower end of the shaft 84 is provided wheel may be rigidly adjusted while in the construction.

of Figure 4, the guide wheel 92 may move upwardly and downwardly when the spring 88 is compressed or expanded.

A clamp bolt 100 with a wing nut Hi2 thereon extends through the aligned cars 14 and 16 and a corrugated friction washer 104 is disposed between the cars 14 and 16 for imparting a frictional resistance to pivotal movement of the bar 12 in relation to the bar 18 but which will permit such movement under certain conditions.

These conditions are the movement of the wheel 92 over an irregular surface such as the periphery of a pipe wherein the magnet 42 will retain a fixed pivot point While the wheel 92 guides movement of the torch 70 and retains the torch 70 with the flame in perpendicular relation to the material being cut thereby making the most efiicient cut employing the hottest type of flame since it is well known that when the flame engages the surface to be cut at an angle that a portion of the heat is reflected substantially in the manner of a light beam. Thus by providing the frictional joint or connection between the arms 12 and 18, the torch 70 may be easily maintained in the optimum condition or position for the best results and the entire device is compact, easy to carry and relatively inexpensive to manufacture.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A circle cutting attachmentfor cutting torches comprising an elongated arm having two sections, means adjustably mounted on said arm for locating and maintaining a center point, a guide wheel adjustably and resiliently mounted on one end of said arm, an adapter for attachment to a cutting torch rotatably mounted on said arm adjacent said guide wheel, and a pivot joint in said arm between said sections adjacent the adapter for permitting vertical swinging movement of the adapter, said sections having ears on the ends thereof containing apertures therein and adapted to cooperate with each other, said apertures being in aligned condition and containing a bolt therethrough and having a wing nut on the end thereof, a corrugated friction washer on said bolt between said ears providing said pivot joint between said sections to frictionally prevent free movement but to permit the weight of the torch to move the adapter in conformance with changes in the contour of the work, said center point locating rneans including a permanent magnet and resilient spring means connecting said permanent magnet to said elongated arm.

2. A circle cutting attachment for cutting torches comprising an elongated arm, means adjustably mounted on said arm for locating and maintaining a center point, a guide wheel adjustably and resiliently mounted on one end of said arm, an adapter for attachment to a cutting torch rotatably mounted on said arm adjacent said guide wheel, and a pivot joint in said arm adjacent the adapter for permitting vertical swinging movement of the adapter, said pivot joint including, friction producing means to prevent free movement but to permit the weight of the torch to move the adapter in conformance with changes in the contour of the work, said pivot joint further including locking means said adapter including a ball bearing-assembly including an outer race rigid with the arm and an inner race rotatable in relation to the outer race, a cylindrical fitting disposed in said inner race, said fitting having screw threads for engagement with the torch, said fitting being-provided with a split ring at one end and a lateral projection in spacedrelationthereto for locking the fitting in the inner race, said assembly having closure plates thereon with theupper closure plate being integral with the outer race and the lower closure plate being held in position by the split ring.

References Cited in the tile of this patent UNITED STATES PATENTS 1,139,048 Messer May 11, 1915 1,351,846 Forster Sept. 7, 1920 2,170,305 Ingwersen l Aug. 22, 1939 2,424,286 Robbins July 22, 1947 2,460,826 Hooser et a1. Feb. 8, 1949 FOREIGN PATENTS 201,483 Germany Sept. 11, 1908 549,923 Great Britain Dec. 14, 1942 

